Cardiac output may be measured using a thermo-dilution technique where a fluid, such as chilled water may be injected into the blood stream and the measured temperature decay rate, i.e., the warming in the local area of injection over time, is used to indicate or infer cardiac volumetric output. The injectate temperature and volume provide an initial condition for a process of a homeothermic organism that may be simulated. That is, as the temperature of the blood fluid proximate to the injection point rises over a period of time toward the expected homeothermic level, one may infer the blood volume flow causing the measured temperature increase.
FIG. 1 illustrates a setup or system for measuring cardiac output using a thermo-dilution technique. A catheter 100 is inserted into an artery 101 of a human patient's flesh 102, e.g., into an artery of a person's upper arm. At the distal end of the catheter or a lumen within, or extending from, the catheter is shown with a thermistor 103 for measuring blood temperature. To initiate a thermo-dilution cardiac output measurement  process, cold fluid is injected into the artery through the catheter via a syringe 104. The temperature of the injected fluid is measured by an injectate temperature thermistor 105. Both the blood temperature thermistor and the injectate temperature thermistor make electrical connections to a cardiac output computer 106 via electrical connectors 107, 108 and cables 127, 128. A cardiac output computer 106 may include a central processing unit (CPU), addressable memory, a display 109, and an input panel 110.
For training and testing purposes it is often useful to simulate a cardiac output measurement and provide a display of a representative value of cardiac output. Simulators may simulate both the blood temperature and injectate temperature thermistors. The thermistors 103 used for blood temperature sensing in FIG. 1 typically have standard electrical properties and typically use a standard electrical connection 107, however the thermistors used for injectate temperature sensing may not have standard electrical properties and/or may not use a standard connection. Accordingly, cardiac output simulators generally may be in electrical communication via vendor-specific adapter cables which comprise one or more vendor-specific fixed resistance values to simulate injectate temperature and the vendor-specific injectate temperature connector. The vendor-specific adapter cables are typically relatively expensive and bulky.